HIV/AIDS Disease Progression[unreadable] [unreadable] Psychosocial factors (e.g., depression, avoidant coping, life stress) have been related to disease progression in HIV, but the relationship between stable personality traits and disease progression has gone virtually unexplored.[unreadable] [unreadable] We examined the relationship between the Five-Factor Model (FFM) dimension of Conscientiousness and HIV disease progression (CD4 cell and viral load) over 1 year in 119 seropositive participants. Conscientiousness was specifically examined because of its known relationship with health-related behaviors and coping. We also examined whether Conscientiousness effects were mediated by adherence, perceived stress, depression, or coping measures. Conscientiousness predicted significant increases in CD4 number and significant decreases in viral load at 1 year. Conscientiousness was related positively to medication adherence and active coping and negatively to depression and perceived stress. Only perceived stress emerged as a possible mediator. The significant relationship between Conscientiousness and medication adherence, distress, and coping suggests that an assessment of Conscientiousness in patients with HIV may help specify or target behavioral interventions to promote optimal disease management. Directions for future work include examining the other personality domains of the FFM, and to study disease progression over a longer period of time to better assess the effects of personality.